/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.http.protocol;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

/**
 * Maintains a map of objects keyed by a request URI pattern. <br>
 * Patterns may have three formats:
 * <ul>
 * <li><code>*</code></li>
 * <li><code>*&lt;uri&gt;</code></li>
 * <li><code>&lt;uri&gt;*</code></li>
 * </ul>
 * <br>
 * This class can be used to resolve an object matching a particular request
 * URI.
 * 
 * @since 4.0
 */
public class UriPatternMatcher {

	/**
	 * TODO: Replace with ConcurrentHashMap
	 */
	@SuppressWarnings("rawtypes")
	private final Map map;

	@SuppressWarnings("rawtypes")
	public UriPatternMatcher() {
		super();
		this.map = new HashMap();
	}

	/**
	 * Registers the given object for URIs matching the given pattern.
	 * 
	 * @param pattern
	 *            the pattern to register the handler for.
	 * @param obj
	 *            the object.
	 */
	@SuppressWarnings("unchecked")
	public synchronized void register(final String pattern, final Object obj) {
		if (pattern == null) {
			throw new IllegalArgumentException(
					"URI request pattern may not be null");
		}
		this.map.put(pattern, obj);
	}

	/**
	 * Removes registered object, if exists, for the given pattern.
	 * 
	 * @param pattern
	 *            the pattern to unregister.
	 */
	public synchronized void unregister(final String pattern) {
		if (pattern == null) {
			return;
		}
		this.map.remove(pattern);
	}

	/**
	 * @deprecated use {@link #setObjects(Map)}
	 */
	@Deprecated
	@SuppressWarnings("unchecked")
	public synchronized void setHandlers(
			@SuppressWarnings("rawtypes") final Map map) {
		if (map == null) {
			throw new IllegalArgumentException(
					"Map of handlers may not be null");
		}
		this.map.clear();
		this.map.putAll(map);
	}

	/**
	 * Sets objects from the given map.
	 * 
	 * @param map
	 *            the map containing objects keyed by their URI patterns.
	 */
	@SuppressWarnings("unchecked")
	public synchronized void setObjects(
			@SuppressWarnings("rawtypes") final Map map) {
		if (map == null) {
			throw new IllegalArgumentException(
					"Map of handlers may not be null");
		}
		this.map.clear();
		this.map.putAll(map);
	}

	/**
	 * Looks up an object matching the given request URI.
	 * 
	 * @param requestURI
	 *            the request URI
	 * @return object or <code>null</code> if no match is found.
	 */
	public synchronized Object lookup(String requestURI) {
		if (requestURI == null) {
			throw new IllegalArgumentException("Request URI may not be null");
		}
		// Strip away the query part part if found
		int index = requestURI.indexOf("?");
		if (index != -1) {
			requestURI = requestURI.substring(0, index);
		}

		// direct match?
		Object obj = this.map.get(requestURI);
		if (obj == null) {
			// pattern match?
			String bestMatch = null;
			for (@SuppressWarnings("rawtypes")
			Iterator it = this.map.keySet().iterator(); it.hasNext();) {
				String pattern = (String) it.next();
				if (matchUriRequestPattern(pattern, requestURI)) {
					// we have a match. is it any better?
					if (bestMatch == null
							|| (bestMatch.length() < pattern.length())
							|| (bestMatch.length() == pattern.length() && pattern
									.endsWith("*"))) {
						obj = this.map.get(pattern);
						bestMatch = pattern;
					}
				}
			}
		}
		return obj;
	}

	/**
	 * Tests if the given request URI matches the given pattern.
	 * 
	 * @param pattern
	 *            the pattern
	 * @param requestUri
	 *            the request URI
	 * @return <code>true</code> if the request URI matches the pattern,
	 *         <code>false</code> otherwise.
	 */
	protected boolean matchUriRequestPattern(final String pattern,
			final String requestUri) {
		if (pattern.equals("*")) {
			return true;
		} else {
			return (pattern.endsWith("*") && requestUri.startsWith(pattern
					.substring(0, pattern.length() - 1)))
					|| (pattern.startsWith("*") && requestUri.endsWith(pattern
							.substring(1, pattern.length())));
		}
	}

}
